Machine for finishing thermophones



A. M. VAN DOORN.

MACHINE FOR FINISHING THERMOPHONES.

APPLICATION FILED IIIAII. I. 1919.

1,338,887. I Patented May 4, 1920..V

4 SHEETS-SHEET l.

I @fl r TDR/Veys:

A. M. VAN DOORN.

MACHINE FOR.FINSHING THERMOPHONES.

APPLICATION rlLED MAR.1, 1919.

v Patented May 4, 1920.

. 4 SHEETS-SHEET 2.

A.M. vAN'DooRN.

MACHINE FOR FINISHING THERMQPHUNES.

APPLICATION ITILED MAR..1 1919.

Patented May 4,1920.

4 SHEETS-SHEET 4.

Fig. M.

UNITED STATES PATENT OFETCE.

ANTHONIUS M. VAN DOORN, 0E NEWTON, MASSACHUSETTS, ASSIGNCR, vEY MESNE ASSIGNMENTS, To AMERICAN THERMOPHCNE COMPANY, 0E BOSTON, MASSA- CHUSETTS, A CORPORATION 0E MASSACHUSETTS.

MACHINE FOR FINISHING THERMOPHONES.

Specification of Letters Patent.

Patented May 4, 1920.

To all 'whom t may Concern.'

Be it known that I, ANTHONIUS M. VAN DOORN, of Utrecht, Holland, a subject of Wilhelmina, Queen of the Netherlands, residing in Newton, Massachusetts, have invented a new and useful Improvement in Machines for Finishing Thermophones, of which the following is a specification.

In an application for United States Letters Patent filed contemporaneously herewith, Serial No. 280,167, I have described a machine for making what may be called a thermophone blank, that is to say, a partially constructed thermophone, my present invention relating to a machine for the completion of the thermophone. As stated in my companion application, the completed article is a device approximately half an inch in diameter and three eighths of an inch high (see Figure 12) and contains a series of looped conductors arranged electrically in parallel comprising Wollaston wires which at their base are ten microns in diameter and where the metal coating has been etched therefrom 2 microns in diameter. The constructing of the thermophone must be conducted with great care to avoid breakage, and at the same time the construction should be such that the electrical resistance of each loop shall be slightly over an ohm and where, as shown in the drawings, there are 18 loops arranged in parallel the total resistance of the device shall be approximately 22 ohms.

For the make-up of a blank, wires approXimately 7-1- mm. in length are used and in the final operation of finishing the thermophone a length of 5-3 mm. is etched-from its middle, leaving a corresponding length of its core of preferably platinum wire eX- posed to furnish the heater. The whole device, therefore, is one 'of Such size and delicacy that it is very difficult to construct, otherwise than by the most careful manipilation or the most accurate machinery.

y present invention will be understood by reference to the drawings yin which a machine for finishing the mechanical Structure of the thermophone is Shown in its preferred form and wherein Fig. 1 is a side elevation, and

Fig. 2 a longitudinal section on line 2 2 of Fig. 3 of a machine embodying my invention.

Fig. 3 is a section on line 3-3 of Fig. 1, and

Fig. 4 is a section on line 4-4 of Fig. 1.

Figs. 5, 7, 8 and 9 show the operation of the machine upon the blank.

- Fig. 6 being a side elevation of one of the tools.

Eig. 1o Shows .the blank in form to bj made up by the machine.

Fig. 1l ,is a side elevation of the blank4 aftder it has beenfinished by the machine, an

Fig. 12 shows a longitudinal section of the finished thermophone and its cover.

Referring to Figs. 1 to 4, inclusive, A is a base or table which is slotted as at a and has onk its upper surface tracks A1. A work holder B is mounted on the tracks A1 and is clamped in position by a screw b. It has two uprights .carrying bushings b1 constructed preferably with ball bearings 62, 723 in which is mounted a Sleeve C in such a manner that the sleeve may be revolved. lFor this purpose the sleeve C car-` ries at its rear end a pulley D. Within the sleeve C is a Spindle E which is reduced at one end as at e to a shape to assist in the loop-forming operation below described and is still further reduced to provide a threaded end or screw e1 to receive a nut to hold the work in place. The spindle is also grooved as at e2 to receive a screw es which passes through the sleeve C, to cause the rotation of the spindle with the rotation of the sleeve and at the same time ,to allowv the spindle to have a longitudinal movement with relation to the sleeve.

lThe spindle at its outer end carries a knurled handle E1 and also a cross-arm E2 of suitable shape to engage shouldered pins d, Z1 projecting rearwardly from the pul-l ley D. By means'of the handle the spindle may be moved longitudinally and by means of the shoulders on the pins d, Z1 and crossarm E2 the spindle is locked forward or"` back and power is transferred from the pulley to rotate it. v

The construction of these parts is such that the application of power by means of a suitable belt on the pulley D will rotate both the Sleeve and the spindle at all times, but at any moment the spindle may be moved longitudinally in such a way that its end will project from the sleeve as shown,

in Figs. 1, 2, 5, 8 and 9, or may be retracted as shown in Fig. Y

On the rails A1 is also mounted a sliding support F for atool rest F1. On the sliding support F is mounted a cross slide F2. The cross slide F2 has a hub F3 having a socket in which sets a stud f forming the lower portion of the tool rest F1. f1 is a strap which surrounds a split sleeve f2 forming an upward extension of the hub IFS as well as the stud f, and f3 is a screw which passes through the ends of the strap f1 and is operated by a handle f4 so as to clamp the strap around the sleeve and stud f and so clamp the tool holder in place.

Gr is a screw which passes up through the slot a inthe base A and screws into a dovetail nut G1 which is mounted on the upper side of the slide F and in a dovetail groove in the cross slide F2 so that upon tightening the screw Gr the parts are clamped together in place on the rails. When the screw G is loosened the cross slide F2 may be adjusted crosswise of the machine and also may be turned at an angle to the spindle if desired. When lproper adjustment has been reached the tightening of the screw G will hold the parts in proper position.. A slight adjustment of the angle of the tool rest to the spindle may be had by loosening the handle f4.

It will be noted that the blank to be formed into a thermophone on this machine comprises a core 1 surrounded by a clamping piece or a thimble Q'crimped in to the form of the periphery of the core, and a plurality of wires 8 projecting straight outwardly therefrom, all of the same length (see Fig. 1() where the blank is shown in side elevation and Fig. 5 where these parts may be identified). In this form it comes from the machine first above referred to. The operation to be carried out by this machine is the bending of the wires into'loops (see Fig. 1l) and the :fastening of their' free ends after they have been so bent to a metallic part whichV may form an electrode.

For this purpose the spindle E is pushed forward (see Figs. 1, 2, 5, 8 and 9) and there is first placed upon the threaded end e1 of-it the'blank shown in Fig. 10, the interior of the core 1 being preferably threaded for this purpose as'shownin Fig. 12. This gives the -wires 3 their initial bend (see iF ig. 5). 'ljhere is next placed upon the threaded portion c1 of the spindle a former H, that is, a cyllndrical metal piece closed at one end except for a threaded opening to enable it to be screwed onto the screw el, its cylindrical part being of sufficient length and properly shaped toallow the wires 3 to be bent over its outer edge. l It also hasa shoulder h against whichthe ends of the loops are bent (see Fig. '7). There is then preferably placed upon the same screw e41 a spacer J, which isshaped to lit over the former H,but has deep serrations j providing points jl the purpose of which is to enter between the various wires 3 and so arrange and space them before they are finally bent as to prevent their being entangled during the forming operation. A nut e4 is then screwed to the threaded portion el to give the wires a preliminary bending by forcing them against the shoulder c5 (see Fig. 5 in which the wires are shown engaging the shoulder e5 and bent outwardly thereby). The spacer J is then removed and the nut replaced and the spindle E is then drawn within the sleeve C so that this end of the sleeve C and the former H will coperate to double back the wires 3 (see Fig. 7 y

is a split ring which is carried by the sleeve C and is placed on the sleeve before the blank is put in place, and when the spacer has been removed this ring is slipped off the sleeve and infront of it so that it will engage the wires and iron them against the former H. The former is then removed and a properly shaped piece of bakelite or the like insulator 4 is placed around the core 1YV and forced between the thimble 2 and the ring K which holds the wires in position, thus insulating the electrodes from each other. The nut c* is then removedand the thimble 5 is then placed over the blank, the nut c4 being replaced and screwed Vup to force the parts into final position and the ends 6 ofthe loops about the ring K (see` Fig. 8)'. The thimble 5 is then crimped or spun by a hand tool of proper shape resting on the tool restfF3L into engagement with the periphery of the insulator and also around the ring K, thus attaching the loops firmly to the ring (see Fig. 9). The thermophone is then finished except for the addition thereto of the cover member 7 c which lits down over, and may be attached to, the base of the thermophone in any desired way, forming a resonance chamber the walls of which coperate with the compressional waves caused bythe changes in temperature in the loops. Before this cover '7 is put on, however, it is necessary that the loops shallvv be etched byV means of any suitable acid to remove a portion of the coating of the Wollasten wire, this being done by dipping the tips of the loops into the acid` for a predetermined length. It is vnecessary that .this be` done accurately in Vorder that a standard o f resistance in thermophones may be main'- tained and also so that the resistanceof each loop shall be substantially the same as that of `every other loop, this forming apart of a contemporaneous application.

Vhile my invention may be otherwise embodied, the above described is a simple and convenient means for accomplishing the desired result. The hand tool referred to is not shown, as it may be of any convenient shape depending upon the work to be done, as will be understood by any lathe worker.v

What l claim as my invention is l. A machine of the kind described comprising a longitudinally movable spindle, a sleeve located about said spindle, said spindle and said sleeve being connected whereby they will rotate together, said spindle being provided at one end with means to attach a blank thereto, and having a means located near said end whereby wires projecting from said blank may be deflected outwardly in the act of attaching said blank to said spindle.

2. A machine of the kind described comprising a longitudinally movable spindle, a sleeve located about said spindle, said spindle and said sleeve being connected whereby they will rotate together, said spindle being provided at one end with means to attach a blank thereto, and having a means` located near said end whereby wires projecting from said blank may be deflected outwardly in the act of attaching said blank to said spindle, in combination with a forming means located to engage said wires laterally as they are deflected and determine their point of deflection.

3. A machine of the kind described comprising a longitudinally movable spindle, a sleeve located about said spindle, said spindle and said sleeve being connected whereby they will rotate together, said spindle being provided at one end with means to attach a blank thereto, and having a means located near said end whereby wires projecting from said blank may be deflected outwardly in the act of attaching said blank to said spindle, in combination with a forming means located to engage said wires laterally as they are deflected and determine their point of deflection, and means to enter between adjacent wires to prevent them from interengaging.

d. A. machine of the kind described comprising a longitudinally movable spindle, a sleeve located. about said spindle, said spindle and said sleeve being connected whereby they will rotate together, said spindle being provided at one end with means to attach a blank thereto, and having a means located near said end whereby wires projecting from said blank may be dellected outwardly inthe act of attaching said blank to said spindle, in combination with a forming means located to engage said wires laterally as they are deflected and determine their point of deflection, the end of said sleeve being shaped whereby it may bind said deflected wires over said forming means when said spindle is retracted.

5. A machine of the kind described comprising a longitudinally movable spindle, a sleeve located about said spindle, said spindle and said sleeve being connected whereby they will rotate together, said spindle being provided at one end with means to attach a blank thereto, and having a means located near said end whereby wires projecting from said blank may be deflected outwardly in the act of attaching said blank to said spindle, in combination with a forming means located to engage said wires laterally as they are deflected and determine their point of dellection, said forming means being of less diameter than the interior of said sleeve whereby when the spindle is retracted said forming means will be drawn within said sleeve and the deflected wires will thereby be bent down over the forming means.

6. ln a machine of the kind described, a longitudinally movable spindle, a sleeve surrounding said spindle rotatable therewith, a yielding ring carried by said sleeve, said spindle being adapted to carry a blank having wires projecting therefrom, means for deflecting said wires, and means whereby said ring when pushed oil said sleeve will cause said wires to be doubled, and means whereby the ends of said wires will be bent around said ring.

ANTHONIUS M. VAN DOORN, 

